Facility Systems

The four numbers that matter

If you write down suction pressure, discharge pressure, suction-line temperature, and liquid-line temperature, you can compute superheat and subcooling. These two numbers are the first thing any chiller tech asks for. Low superheat with low subcooling usually means low charge. High superheat with low subcooling means low charge or a restriction. High superheat with high subcooling means undercharge with a metering problem. Memorize the combinations, and diagnostics gets much faster.

The cooling tower is the cheapest thing to ignore

Until it is not. Scale and biological fouling quietly double your chiller energy bill. Start with water chemistry. Conductivity, pH, biocide residual, scale inhibitor dose. If any of these are drifting, the tower is the source. Fan bearings and motor drives also live out in the weather and fail first of anything in the central plant.

A few things that will save you a call

Cooling problems often are not cooling problems.

• Low charge is the most common chiller complaint. Find the leak before topping off, or you will be back next month.
• Fouled condenser tubes look like a capacity problem. A quarterly ball-cleaning program keeps them open.
• Sensor drift causes ghost alarms. Calibrate the refrigerant suction and discharge transducers yearly.
• BMS setpoint drift happens quietly. Someone bumps a value to solve a complaint, and it never gets reset.

What you do not touch

Refrigerant circuit work requires an EPA-certified technician in most jurisdictions. Compressor rebuilds belong at the OEM. For tower fan bearings at height, bring in a contractor with proper fall protection. The cost of an injury far exceeds the cost of a professional.